The first black firebox from Rüegg

Rüegg is proud to be able to equip heating units with the unique Thermobrikk® as the first manufacturer in the world since 2013. The new black firebox has amazing physical properties which even astonish the experts.


Thermobrikk® is the first black firebox to live up to its promises: It stays dark even after numerous burn-ups and, with its timeless elegance, meets the modern aesthetic demands brilliantly. In addition, Thermobrikk® has outstanding physical properties which are reflected in durability, robustness and positive influences on the combustion process. Heating units equipped with Thermobrikk® set new benchmarks when it comes to cleanliness and efficiency – even in view of limits which will become even more strict in the future.

Thermobrikk® features:

  • Black firebox, high robustness
  • Specific weight (kg/dm3): 1.7
  • Material: The composition remains a secret, all of the ingredients are natural products
  • Cutting capacity: Good to very good, hardly crumbles at all
  • Thermal properties: Very good, reduces emissions, increases the efficiency level
  • Installation: Easy and problem-free thanks to high modularity
  • Look: Lastingly very good

No solution in sight for a long time

For years, fireclay producers have been on the hunt for a formula for the production of a firebox lining which is as black as possible, which is able to fulfil the modern aesthetic requirements and keeps its dark colour even after long-lasting fires. However, all of the research and tinkering only ever yielded poor pickings. Consequently, the desire for dark material is still today largely met with black steel. Although this variant has its charm, steel fireplaces have thermal properties which are clearly inferior to fireclay fireplaces: You buy the desired aesthetic with significantly poorer combustion processes, meaning higher pollutant emissions and lower efficiency levels.

Inventor tested thousands of mixing ratios

But one inventor in his small, unimposing laboratory didn’t want to settle for this situation and was dead set on developing a black firebox lining. With passion, persistence and great talent, he set to work. And he did it all alone!

He analysed thousands of mixing ratios, processed ingredients from adventurous geological areas of the planet and pressed hundreds of material samples. Our “Gyro Gearloose” subjected the samples thus obtained to every conceivable endurance test and was disappointed hundreds of times as a result. The material lost either its colour, its solidity, its texture, its sharp edges, its physical properties or any combination of the above. With time, he came upon a clue which encouraged him to continue with the exhausting and sometimes frustrating attempts. Always driven by the conviction that a black firebox – as it worked in practical operation – would have outstanding chances of success on the market.

The endurance test that astonished everyone

One day in 2011, the inventor presented the astonished Rüegg representatives with an unimposing tile: Almost black, very smooth surface structure and extraordinarily fine edges. Rüegg demanded the most challenging tests. The inventor was asked to subject the material to relentless endurance testing. This included heating up to red heat and then quenching in cold water, breaking load tests, impact resistance tests, grinding tests and cutting tests. And every attempt to bring the material to its knees failed miserable, it emerged from the tests like a phoenix from the ashes. Even the colour was unchanged. The world of fire had never seen anything like it. The invention was patented, of course, and gained the name of Thermobrikk®.

Thermobrikk® – a name to remember!

Many heating units from Rüegg are already fitted with Thermobrikk and can naturally also be retrofitted with it. The lining with Thermobrikk is consistently modularly built and consists of individual elements which work according to the modular principle. Replacing an element (if there is ever any need) is very simple and can be done by the fireplace owner themselves.

Rüegg units with Thermobrikk®: